Blended operation mode for providing cooling to a heat load

ABSTRACT

Conditioning systems and methods for providing cooling to a heat load can include an evaporative cooler arranged in a scavenger plenum with a recovery coil downstream of the evaporative cooler. The conditioning systems can operate in various modes, including an adiabatic mode and an evaporative mode, and a blended mode between the adiabatic mode and the evaporative mode, depending on environmental conditions. The blended mode can be enabled by a fluid transmission and retention device fluidically connected to the inlet and outlet of the evaporative cooler, the recovery coil outlet, and the heat load. The fluid transmission and retention device can variably distribute the cooling fluid exiting the recovery coil and the cooling fluid exiting the evaporative cooler to one or both of the heat load and the evaporative cooler inlet. In an example, the fluid transmission and retention device includes a manifold. In another example, the fluid transmission and retention device includes one or more tanks.

CLAIM OF PRIORITY

This application is a Continuation in Part of U.S. patent applicationSer. No. 16/764,702, filed on May 15, 2020, which is a U.S. NationalStage Application of PCT Application No. PCT/CA2018/051461, filed onNov. 16, 2018 and published on May 23, 2019 as WO 2019/095070, whichclaims the benefit of U.S. Provisional Patent Application No.62/588,153, filed on Nov. 17, 2017, the benefit of priority of which isclaimed hereby, and which are incorporated by reference herein in theirentirety.

BACKGROUND

There are many applications where cooling is critical, such as, forexample, data centers. A data center usually consists of computers andassociated components working continuously (24 hours per day, 7 days perweek). The electrical components in a data center can produce a lot ofheat, which then needs to be removed from the space. Air-conditioningsystems in data centers can often consume more than 40% of the totalenergy.

With the current data centers' air-conditioning systems and techniquesand significant improvements in IT components operating conditions andprocessing capacity, servers can roughly operate at 50% of theircapacity. This capacity limitation is due, in part, to the coolingsystems not being able to cool the servers efficiently and the serversreach their high temperature limit before reaching their maximumprocessing capacity. High density data center cooling seeks to coolservers more effectively and increase the density of the data centers.Consequently, this will result in savings in data center operating costand will increase the data center overall capacity.

OVERVIEW

The present application relates to conditioning systems and methods forproviding cooling to a heat load. The conditioning systems can includedifferent operating modes and selection of a particular mode can dependon the outdoor air or environmental conditions. The present inventor(s)recognized that additional benefits can be achieved through operatingthe conditioning system under a blended operation mode rather thanshifting entirely from one discrete mode to another. The blended mode isa blend of the capacity/capability of the system between two standardmodes of operation, including, for example, between an adiabatic and anevaporative mode.

The heat load that needs cooling can be any type of device or systemthat generates heat. The device or system can be enclosed or open to theatmosphere. In an example, the heat load can be from a data center. Theconditioning systems and methods of the present application include anevaporative cooler arranged in a scavenger air plenum with a recoverycoil arranged downstream of the evaporative cooler. The system isgenerally designed to deliver conditioned (e.g., cooled) liquid from oneor both of the evaporative cooler and the recovery coil to the heatload. In some modes, the system is able to use only the recovery coil tocool the liquid and deliver all of the recovery coil liquid to the heatload. In such circumstances, the evaporative cooler can be completelybypassed and/or deactivated (and, in some cases, drained of liquid) torun in a dry or economizer mode, or the evaporative cooler can run in anadiabatic mode in which none (or nearly none) of the cooled liquid fromthe evaporative cooler is used for the heat load, and the cooling fluidexiting the evaporative cooler is, instead, returned to the inlet of thedevice.

Systems and methods according to this disclosure also include a fluidtransmission and retention device fluidically connected to the inlet andoutlet of the evaporative cooler, an outlet of the recovery coil, andthe heat load. The fluid transmission and retention device is configuredto variably distribute the cooling fluid exiting the recovery coil andthe cooling fluid exiting the evaporative cooler to one or both of theheat load and the inlet of the evaporative cooler to allow the system tooperate in an adiabatic mode, an evaporative mode, and a blended modefunctionally and operatively between the adiabatic and evaporativemodes. In some examples, the fluid transmission and retention deviceincludes one or more tanks. In another example, the fluid transmissionand retention device includes a manifold.

This overview is intended to provide an overview of subject matter inthe present application. It is not intended to provide an exclusive orexhaustive explanation of the invention. The detailed description isincluded to provide further information about the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 is a schematic of an example conditioning unit for providingliquid cooling.

FIG. 2 is a perspective view of an example tank for use in theconditioning unit of FIG. 1.

FIG. 3 is a top view of the tank of FIG. 2.

FIG. 4 is a perspective view of a portion of the tank of FIG. 2.

FIG. 5 is a simplified schematic showing a side view of a discharge tubeof the tank.

FIG. 6 is a simplified schematic showing a top view of the dischargetube of the tank.

FIG. 7 is a perspective view of an example tank for use in theconditioning unit of FIG. 1.

FIG. 8 is a simplified schematic of the conditioning unit of FIG. 1.

FIG. 9 is a psychometric chart of a conditioning unit operating in anadiabatic mode.

FIG. 10 is a psychometric chart of the conditioning unit of FIG. 9operating under the same outdoor air conditions but in an evaporationmode.

FIG. 11 is a chart comparing annual water usage of two differentconditioning systems.

FIG. 12 is a simplified schematic of another example conditioning unit.

FIG. 13 is a schematic of another example conditioning unit having amanifold for operation in the various modes.

FIG. 14 is a schematic of another example conditioning unit having amanifold for operation in the various modes.

DETAILED DESCRIPTION

The conditioning systems and methods of the present application caninclude an evaporative cooler arranged in a scavenger air plenum with arecovery coil arranged downstream of the evaporative cooler. Theconditioning systems and methods can include different operating modesincluding an economizer mode in which the evaporative cooler is off orbypassed, an adiabatic mode and an evaporative mode. Additional benefitscan be achieved through operating under a blended operation mode that isa blend between the adiabatic and evaporative modes. In some examples,the conditioning systems can include a pre-cooler arranged upstream ofthe evaporative cooler for pre-conditioning the scavenger air. Theinclusion of the pre-cooler can allow for additional operating modes.International Application No. PCT/CA2017/050180, published as WO2017/152268, describes conditioning systems having these threecomponents (pre-cooler, evaporative cooler, and recovery coil).

The conditioning systems and methods described herein can include afluid transmission and retention device fluidically connected to theinlet and outlet of the evaporative cooler, an outlet of the recoverycoil, and the heat load. The fluid transmission and retention device canenable operation in the blended mode. The fluid transmission andretention device is configured to variably distribute the cooling fluidexiting the recovery coil and the cooling fluid exiting the evaporativecooler to one or both of the heat load and the inlet of the evaporativecooler to allow the system to operate in the adiabatic mode, theevaporative mode, and the blended mode, as well as the economizer mode.As described below, the fluid transmission and retention device caninclude one or more tanks. In other examples described below, the fluidtransmission and retention device can include a manifold.

FIG. 1 illustrates a conditioning unit 10 that can be used to producecold water for liquid cooling or air cooling of an enclosed space or adevice. The conditioning unit 10 can operate in a blended mode betweenthe adiabatic mode and the evaporative mode, as described below. In anexample, the conditioning unit 10 can provide cooling to a data center.In an example, the conditioning unit 10 can be one of many units thatmake up a conditioning system to provide cooling to a heat load. In theapplication of data center cooling, for example, numerous units can makeup the conditioning system to meet the heat load of the data center. Theconditioning unit 10 can be in fluid connection with a hot water mainand a cold water main, either or both of which can be dedicated to theconditioning unit or be in fluid connection with additional conditioningunits. The cold-water main is indicated in FIG. 1 as cold water to datacenter (cold water 12) and the hot-water main is indicated in FIG. 1 ashot water from data center (hot water 14). In an example, large pipes(ring main) can be used to circulate the hot 14 and cold 12 water to andfrom the heat load.

The conditioning unit 10 can include one or more pre-coolers (PC) 16,one or more evaporative coolers (EC) 18, and one or more recovery coils(RC) 20. The one or more recovery coils 20 can also be referred toherein as dry coils or cooling coils. The one or more pre-coolers 16 canalso be referred to herein as pre-cooling coils, pre-cooler coils,pre-conditioners or dry coils. The pre-coolers 16 can be referred toherein as first cooling components (upstream of the evaporative coolers18) and the recovery coils 20 can be referred to herein as secondcooling components (downstream of evaporative coolers 18).

The conditioning unit 10 can include a scavenger air plenum, indicatedby a dotted line 22 in FIG. 1. The plenum 22 can include an air inlet 24and an air outlet 26 through which a scavenger air stream can flow. Thescavenger air plenum 22 can also be referred to as a housing, cabinet orstructure and can be configured to house one or more components used tocondition air or water. The plenum 22 can be disposed outside of anenclosed space having the heat load or located external to the devicesthat produce the heat load. The one or more pre-coolers 16, evaporativecoolers 18 and recovery coils 20 can be arranged inside the plenum 22.In some examples, a filter (not shown) can be arranged inside the plenum22 near the air inlet 24. In some examples, a fan or fan array (notshown) can be arranged inside the plenum 22 near the air outlet 26.

In the example conditioning unit 10 shown in FIG, 1, two pre-coolers 16(PC-1, PC-2) are shown, three evaporative coolers 18 (EC-1, EC-2, EC-3)are shown, and two recovery coils 20 (RC-1, RC-2) are shown. It isrecognized that more or less of each of the components (PC, EC, RC) canbe included in the conditioning unit. As described above, the pre-cooler16 can selectively operate depending on outdoor air conditions. In otherexample conditioning units, the pre-cooler 16 can be excluded.

As shown in FIG. 1, the conditioning unit 10 can include a tank 28 influid connection with a first pump 30 (P-1) and a second pump 32 (P-2).Water exiting the tank 28 can be delivered to the cold water main 12 viathe first pump 30 (P-1). Water exiting the tank 28 can be delivered tothe evaporative coolers 18 via the second pump 32 (P-2). The single tank28 can be filled with water and thermal isolation can be created bymanaging the flow of warm and cold water into two pump suction bays, asdescribed further below in reference to FIGS. 2-8. Cold water from theevaporative coolers 18 can be input into the tank. Warm or hot waterfrom the recovery coils 20 can be input into the tank 28 through twodifferent inlets, as represented by the two input arrows in FIG. 1 fromthe recovery coils 20 into the tank 28. The tank 28 can be locatedinside or outside the plenum 22. The pumps 30, 32 can be located insideor outside the plenum 22. The tank 28 can include one or more sensorsfor sensing and monitoring various parameters inside the tank 28, suchas, for example, water level, water temperature, etcetera. The design ofthe tank 28 can also include overflow features as well as a waste drain34 and a recovery drain ring 36.

The scavenger air entering the plenum 22 can pass through the one ormore pre-coolers 16 to precondition the scavenger air. The scavenger airexiting the one or more pre-coolers 16 can then pass through the one ormore evaporative coolers 18. The evaporative cooler 18 can be configuredto condition the scavenger air passing there through using anevaporative fluid, such as water. The evaporative cooler 18 can use thecooling potential in both the air and the evaporative fluid to rejectheat. In an example, as scavenger air flows through the evaporativecooler 18, the evaporative fluid, or both the scavenger air and theevaporative fluid, can be cooled to a temperature approaching the wetbulb (WB) temperature of the air leaving the pre-cooler 16. Due to theevaporative cooling process in the evaporative cooler 18, a temperatureof the evaporative fluid at an outlet of the evaporative cooler 18 canbe less than a temperature of the evaporative fluid at an inlet of theevaporative cooler 18; and a temperature of the scavenger air at anoutlet of the evaporative cooler 18 can be less than a temperature ofthe scavenger air at an inlet of the evaporative cooler 18. In somecases, a temperature reduction of the evaporative fluid can besignificant, whereas in other cases, the temperature reduction can beminimal. Similarly, a temperature reduction of the scavenger air canrange between minimal and significant. In some cases, the scavenger airtemperature can increase across the evaporative cooler 18. Suchtemperature reduction of one or both of the evaporative fluid and thescavenger air can depend in part on the outdoor air conditions(temperature, humidity), operation of the pre-cooler 16, and operationof the evaporative cooler 18. In an example, the evaporative cooler 18can selectively operate adiabatically, in which case a temperature ofthe evaporative fluid circulating through the evaporative cooler 18 canremain relatively constant or undergo minimal changes.

The evaporative cooler 18 can be any type of evaporative coolerconfigured to exchange energy between an air stream and a cooling fluidthrough evaporation of a portion of the fluid into the air. Evaporativecoolers can include direct-contact evaporation devices in which theworking air stream and the liquid water (or other fluid) stream that isevaporated into the air to drive heat transfer are in direct contactwith one another. In what is sometimes referred to as “open”direct-contact evaporation devices, the liquid water may be sprayed ormisted directly into the air stream, or, alternatively the water issprayed onto a filler material or wetted media across which the airstream flows. As the unsaturated air is directly exposed to the liquidwater, the water evaporates into the air, and, in some cases, the wateris cooled.

Such direct-contact evaporation devices can also include what issometimes referred to as a closed-circuit device. Unlike the opendirect-contact evaporative device, the closed system has two separatefluid circuits. One is an external circuit in which water isrecirculated on the outside of the second circuit, which is tube bundles(closed coils) connected to the process for the hot fluid being cooledand returned in a closed circuit. Air is drawn through the recirculatingwater cascading over the outside of the hot tubes, providing evaporativecooling similar to an open circuit. In operation the heat flows from theinternal fluid circuit, through the tube walls of the coils, to theexternal circuit and then by heating of the air and evaporation of someof the water, to the atmosphere.

These different types of evaporative coolers can also be packaged andimplemented in specific types of systems. For example, a cooling towercan include an evaporative cooling device such as those described above.A cooling tower is a device that processes working air and water streamsin generally a vertical direction and that is designed to reject wasteheat to the atmosphere through the cooling of a water stream to a lowertemperature. Cooling towers can transport the air stream through thedevice either through a natural draft or using fans to induce the draftor exhaust of air into the atmosphere. Cooling towers include orincorporate a direct-contact evaporation device/components, as describedabove.

Examples of evaporative coolers usable in the conditioning systems ofthe present application can also include other types of evaporativecooling devices, including liquid-to-air membrane energy exchangers.Unlike direct-contact evaporation devices, a liquid-to-air membraneenergy exchanger (LAMEE) separates the air stream and the liquid waterstream by a permeable membrane, which allows water to evaporate on theliquid water stream side of the membrane and water vapor molecules topermeate through the membrane into the air stream. The water vapormolecules permeated through the membrane saturate the air stream and theassociated energy caused by the evaporation is transferred between theliquid water stream and the air stream by the membrane.

Some or all of the one or more evaporative coolers 18 can include aLAMEE as the evaporative cooler. The LAMEE can also be referred toherein as an exchanger or an evaporative cooler LAMEE. A liquid to airmembrane energy exchanger (LAMEE) can be used as part of a heating andcooling system (or energy exchange system) to transfer heat and moisturebetween a liquid desiccant and an air stream to condition thetemperature and humidity of the air flowing through the LAMEE. Themembrane in the LAMEE can be a non-porous film having selectivepermeability for water, but not for other constituents that form theliquid desiccant. Many different types of liquid desiccants can be usedin combination with the non-porous membrane, including, for example,glycols. The non-porous membrane can make it feasible to use desiccants,such as glycols, that had been previously determined to be unacceptableor undesirable in these types of applications. In an example, themembrane in the LAMEE can be semi-permeable or vapor permeable, andgenerally anything in a gas phase can pass through the membrane andgenerally anything in a liquid phase cannot pass through the membrane.In an example, the membrane in the LAMEE can be micro-porous such thatone or more gases can pass through the membrane. In an example, themembrane can be a selectively-permeable membrane such that someconstituents, but not others, can pass through the membrane. It isrecognized that the LAMEEs included in the conditioning units disclosedherein can use any type of membrane suitable for use with an evaporativecooler LAMEE.

In an example, the LAMEE or exchanger can use a flexible polymermembrane, which is vapor permeable, to separate air and water. The waterflow rate through the LAMEE may not be limited by concerns of carryoverof water droplets in the air stream, compared to other conditioningsystems. The LAMEE can operate with water entering the LAMEE at hightemperatures and high flow rates, and can therefore be used to rejectlarge amounts of heat from the water flow using latent heat release(evaporation).

The cooling fluid circulating through the LAMEE or exchanger can includewater, liquid desiccant, glycol, other hygroscopic fluids, otherevaporative liquids, and/or combinations thereof. In an example, thecooling fluid is a liquid desiccant that is a low concentration saltsolution. The presence of salt can sanitize the cooling fluid to preventmicrobial growth. In addition, the desiccant salt can affect the vaporpressure of the solution and allow the cooling fluid to either releaseor absorb moisture from the air. The concentration of the liquiddesiccant can be adjusted for control purposes to control the amount ofcooling of the scavenger air or cooling fluid within the LAMEE orexchanger.

Membrane exchangers may have some advantages over other types ofevaporative coolers. For example, the LAMEE may eliminate or mitigatemaintenance requirements and concerns of conventional cooling towers orother systems including direct-contact evaporation devices, where thewater is in direct contact with the air stream that is saturated by theevaporated water. For example, the membrane barriers of the LAMEEinhibit or prohibit the transfer of contaminants and micro-organismsbetween the air and the liquid stream, as well as inhibiting orprohibiting the transfer of solids between the water and air. The use ofLAMEEs along with an upstream or downstream cooling coil can result in alower temperature of the water leaving the LAMEE and a higher coolingpotential. Various configurations of cooling systems having a LAMEE canboost performance in many climates. Higher cooling potential andperformance can result in lower air flow and fan power consumption inthe cooling system, which is the main source of energy consumption inliquid-cooling systems. In an example in which the heat load is from adata center, this can increase the overall data center cooling systemefficiency.

Depending upon the application and a number of factors, the evaporativecooler 18 can include any type of evaporative cooler configured toexchange energy between an air stream and a cooling fluid throughevaporation of a portion of the fluid into the air.

In an example, the evaporative fluid from the evaporative cooler 18 canbe collected and delivered to the tank 28 and thus can be used toprovide cooling for the heat load. In other examples described herein,the evaporative fluid from the evaporative cooler 18 is not collectedfor cooling the heat load. In yet other examples, the conditioningsystem 10 can be configured to switch between a configuration in whichthe evaporative fluid exiting the evaporative cooler 18 is collected andtransported to the tank 28 and operating the evaporative cooler 18adiabatically to circulate the evaporative fluid through the evaporativecooler 18 only.

In an example, the evaporative fluid in the evaporative cooler 18 can bewater or predominantly water. It is recognized that other types ofevaporative cooling fluids can be used in combination with water or asan alternative to water in the conditioning systems described herein.

The dry coil or recovery coil 20 can be arranged inside the plenum 22downstream of the evaporative cooler 18. The recovery coil 20 can cool acooling fluid circulating through the recovery coil 20 using the coolingpotential of the scavenger air. The scavenger air exiting theevaporative cooler 18 can be relatively cool and additional sensibleheat from the cooling fluid passing through the recovery coil 20 can berejected into the scavenger air. The recovery coil 20 can produce areduced-temperature cooling fluid that can provide cooling to the heatload. The reduced-temperature cooling fluid exiting the recovery coil 20can flow to the evaporative cooler 18 or the tank 28. The scavenger airexiting the recovery coil 20 can be directed out of the plenum 22 usingone or more fans. The scavenger air can exit the plenum 22 as exhaust.

In an example, the cooling fluid circulating through the recovery coil20 can be water. In an example, the cooling fluid circulating throughthe recovery coil 20 can be the same fluid as the evaporative fluid inthe evaporative cooler 18.

As provided above, in an example, the evaporative fluid in theevaporative cooler 18 can be water. In an example, thereduced-temperature water from the outlet of the evaporative cooler 18can be used to provide cooling to the heat load. The reduced-temperaturewater can flow from the evaporative cooler 18 to the tank 28.

The water from the tank 28 can provide cooling to the heat load bytransporting the water to the heat load. The reduced-temperature watercan provide cooling to the heat load using any known methods to rejectheat from air or one or more devices, and such methods can include, butare not limited to, liquid immersing technology, cold plate technology,rear door heat exchangers, cooling distribution units (CDU), and coolingcoils. In an example, the water can directly cool one or more componentsproducing the heat load. The one or more components can include, but arenot limited to, electrical components. In an example in which the heatload comes from an enclosed space, the water can pass through one ormore cooling coils placed in a path of the supply air in the enclosedspace, and the water in the cooling coils can sensibly cool the supplyair.

After the water provides cooling to the heat load, the water can berecirculated back through the unit 10. The water can be at anincreased-temperature after providing cooling to the heat load becausethe rejected heat from the heat load has been picked up by the water.The increased-temperature water can be transported to the recovery coil20. The dry coil or recovery coil 20 can cool the water using thescavenger air exiting the evaporative cooler 18. At least a portion ofthe reduced temperature water can be sent to the tank 28, depending onan operating mode of the unit 10. In some instances, a portion of thereduced temperature water can be sent to the evaporative cooler 18.

In an economizer mode, all of the water from the recovery coil 20 canbypass the evaporative cooler 18 and go directly to the tank 28. Theeconomizer mode or winter mode can enable the conditioning unit 10 tocool the water using the scavenger air and recovery coil 20, withouthaving to run the evaporative cooler 18. In that situation, there may beno need for evaporation inside the evaporative cooler 18 since the coldoutdoor air (scavenger air) can pass through the evaporative cooler 18and sufficiently cool the water. The recovery coil 20 can also bereferred to herein as an economizer coil since it can he a primarycooling source for the water in the economizer mode. Three modes ofoperation are described further below for operating the conditioningunit 10.

The one or more pre-coolers 16, located upstream of the evaporativecooler 18, can he used to pre-condition the scavenger air entering theplenum 22, prior to passing the scavenger air through the evaporativecooler 18. The pre-cooler 16 can be effective when the temperature ofthe water entering the pre-cooler 16 is lower than the outdoor air drybulb temperature. The pre-cooler 16 can be used in typical summerconditions as well as in extreme summer conditions when the outdoor airis hot and humid. The pre-cooler 16 can depress the outdoor air wet bulbtemperature, thus pre-cooling the scavenger air and heating the water.The pre-cooler 16 can provide more cooling potential in the evaporativecooler 18.

In an example, the pre-cooler 16 can use water from the tank 28 tocondition the scavenger air. Because the pre-cooler 16 uses water fromthe tank 28 as the cooling fluid in the pre-cooler 16, the design of thepre-cooler 16 can be referred to as a coupled pre-cooler. In otherwords, the pre-cooler 16 is designed and configured to use a portion ofthe reduced-temperature water produced by the recovery coil 20 or theevaporative cooler 18 (and intended for cooling the heat load) as thecooling fluid for the pre-cooler 16. In other examples, a cooling fluidcircuit for the pre-cooler 16 can be partially or wholly decoupled fromthe process circuit for the evaporative cooler 18 and recovery coil 20.In that case, the pre-cooler 16 can have an external cooling circuitpartially or wholly separate from the reduced-temperature water producedby the evaporative cooler 18 or recovery coil 20 for process cooling.

The plenum 22 can include one or more sets of bypass dampers forexample, a first set of dampers can be located between the pre-cooler 16and the evaporative cooler 18, and a second set of dampers can belocated between the evaporative cooler 18 and the recovery coil 20. Theuse of the bypass dampers can direct the flow of scavenger air into theplenum 22 depending on the outdoor air conditions.

The conditioning unit 10 can operate in at least three modes andselection of the mode can depend, in part, on the outdoor air conditionsand the heat load. When the outdoor air is cold, the conditioning unitcan operate in a first mode, an economizer mode, and the pre-cooler 16and the evaporative cooler 18 can be bypassed. The scavenger air canenter the plenum 22 downstream of the evaporative cooler 18 and passthrough the recovery coil 20. This can protect the evaporative cooler 18and avoid running the evaporative cooler 18 when it is not needed. Inthe first mode or economizer mode, the scavenger air can be cool enoughsuch that the recovery coil 20 can provide all cooling to the waterdelivered to the tank 28 sufficient to provide cooling to the heat load,without needing to operate the evaporative cooler 18.

In a second operating mode, which can also be referred to as a normalmode or an evaporation mode, the pre-cooler 16 can be bypassed but theevaporative cooler 18 can be used. The evaporation mode can operateduring mild conditions, such as spring or fall, when the temperature orhumidity is moderate, as well as during some summer conditions. Thescavenger air may be able to bypass the pre-cooler 16, while stillmeeting the cooling load. The scavenger air can enter the plenum 22downstream of the pre-cooler 16 and pass through the evaporative cooler18 and the recovery coil 20. In an example, the dampers can be excludedor may not be used in some cases. In such example, during the secondoperating mode, the scavenger air can pass through the pre-cooler 16 butthe pre-cooler 16 can be turned off such that the water or cooling fluidis not circulating through the pre-cooler 16.

In a third operating mode, which can also be referred to as an enhancedmode or a super-evaporation mode, the conditioning unit 10 can run usingboth the pre-cooler 16 and the recovery coil 20. Under extremeconditions, or when the outdoor air is hot or humid, the unit 10 canprovide pre-cooling to the scavenger air, using the pre-cooler 16,before the scavenger air enters the evaporative cooler 18. Thepre-cooler 16 can be used to improve the cooling power of the unit 10,allowing the evaporative cooler 18 to achieve lower dischargetemperatures. The pre-cooler 16 can reduce or eliminate a need forsupplemental mechanical cooling. In an example, a portion of the waterexiting the pre-cooler 16 can be directed to the evaporative cooler 18.In other examples, the cooling fluid circuit of the pre-cooler 16 can bedecoupled from the evaporative cooler 18.

The conditioning system 10 can include a system controller 38 to controloperation of the conditioning system 10 and control an amount of coolingprovided from the cooling system 10 to the heat load (via the cold water12). The system controller 38 can be manual or automated, or acombination of both. The conditioning system 10 can be operated so thata temperature of the water in the tank 28 can be equal to a set pointtemperature that can be constant or variable. In an example, instead ofmeasuring i monitoring a temperature of the water in the tank, atemperature of the water after the water exits the tank (via the secondpump 32) can be measured and compared to the set point temperature. Theset point temperature can be determined based in part on the coolingrequirements of the heat load. In an example, the set point temperaturecan vary during operation of the conditioning unit 10, based in part onoperation of the data center or other devices that produce the heatload.

The system controller 38 can include hardware, software, andcombinations thereof to implement the functions attributed to thecontroller herein. The system controller 38 can be an analog, digital,or combination analog and digital controller including a number ofcomponents. As examples, the controller 38 can include ICB(s), PCB(s),processor(s), data storage devices, switches, relays, etcetera. Examplesof processors can include any one or more of a microprocessor, acontroller, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), orequivalent discrete or integrated logic circuitry. Storage devices, insome examples, are described as a computer-readable storage medium. Insome examples, storage devices include a temporary memory, meaning thata primary purpose of one or more storage devices is not long-termstorage. Storage devices are, in some examples, described as a volatilememory, meaning that storage devices do not maintain stored contentswhen the computer is turned off. Examples of volatile memories includerandom access memories (RAM), dynamic random access memories (DRAM),static random access memories (SRAM), and other forms of volatilememories known in the art. The data storage devices can be used to storeprogram instructions for execution by processor(s) of the controller 38.The storage devices, for example, are used by software, applications,algorithms, as examples, running on and/or executed by controller 38.The storage devices can include short-term and/or long-term memory, andcan be volatile and/or non-volatile. Examples of non-volatile storageelements include magnetic hard discs, optical discs, floppy discs, flashmemories, or forms of electrically programmable memories (EPROM) orelectrically erasable and programmable (EEPROM) memories.

The system controller 38 can he configured to communicate with theconditioning system 10 and components thereof via various wired orwireless communications technologies and components using various publicand/or proprietary standards and/or protocols. For example, a powerand/or communications network of some kind may be employed to facilitatecommunication and control between the controller 38 and the conditioningsystem 10. In one example, the system controller 38 can communicate withthe conditioning system 10 via a private or public local area network(LAN), which can include wired and/or wireless elements functioning inaccordance with one or more standards and/or via one or more transportmediums. In one example, the system 10 can be configured to use wirelesscommunications according to one of the 802.11 or Bluetooth specificationsets, or another standard or proprietary wireless communicationprotocol. Data transmitted to and from components of the conditioningunit 10, including the controller 38, can be formatted in accordancewith a variety of different communications protocols. For example, allor a portion of the communications can be via a packet-based, InternetProtocol (IP) network that communicates data in Transmission ControlProtocol/Internet Protocol (TCP/IP) packets, over, for example, Category5, Ethernet cables.

The system controller 38 can include one or more programs, circuits,algorithms or other mechanisms for controlling the operation of theconditioning system 10. For example, the system controller 38 can beconfigured to modulate the speed of one or more fans in the plenum 22and/or control actuation of one or more valves to direct cooling fluidfrom the outlet of one or more components of the unit 10 to the tank 28.The system controller 38 can also be configured to operate the system 10in the modes described herein.

FIG. 2 shows an example of the design of the tank 28 of FIG. 1. The tank28 can include a first pump suction bay 40, having a first cover 41, anda second pump suction bay 42, having a second cover 43. FIG. 3 shows atop view of the tank 28 of FIG. 2 with the covers 41, 43 removed to showinterior features of the tank 28. The water exiting the evaporativecooler can enter the tank 28 through a discharge break tank 44 at a backend 46 of the tank 28 and the water can be generally free to flow intoeither of the pump bays 40, 42. Such water from the evaporative coolercan be referred to herein as cold discharge water or EC discharge water.The back end 46 of the tank can also be referred to herein as adischarge area since such area of the tank 28 receives the dischargewater from the evaporative cooler. The break tank 44 can be used forback pressure control and energy dissipation. The tank 28 can include adividing baffle 48 for separation of the first and second pump bays 40,42. A front end 49 of the tank 28 can include a first pump suction inlet50 for the first pump suction bay 40 and a second pump suction inlet 52for the second pump suction bay 42.

The tank 28 is configured such that each pump suction bay 40, 42 canreceive return water from the recovery coil and the amount of returnwater delivered to each suction bay 40, 42 can be varied via acorresponding valve 54, 56, respectively. FIG. 2 shows a portion ofpiping 58 from the recovery coil. Although such return water from therecovery coil has been circulated through the recovery coil before beingdelivered to the tank 28, such return water can still be relatively warmor hot in some cases (depending on outdoor air conditions), and thus isreferred to herein as hot return water or RC return water. It isrecognized that under some outdoor air conditions such return water canbe cool or relatively cold. Such return water is also referred to hereinas RC discharge water. The distribution or ratio of hot return waterdelivered to each pump suction bay 40, 42 can be regulated. as describedbelow. The design shown in FIG. 2 includes two modulating two-way valves54 and 56. In other designs, a three-way valve (see FIG. 8) can be usedto control the distribution of return water to the two suction bays 40,42.

Each of the bays 40, 42 can include a recovery drain 60, 62,respectively. An overflow drain/weir 64 can be included at the front end49 of the tank 28 in the second pump suction bay 42.

The first pump suction inlet 50 can be used to transfer water out of thefirst bay 40 and to the first pump 30 such that water can be pumped tothe cold water main 12 to provide cooling to the data center or otherheat load. The second pump suction inlet 52 can be used to transferwater out of the second bay 42 and to the second pump 32 such that watercan be recirculated back to the evaporative coolers 18.

When the conditioning unit 10 is operating, essentially all of the tank28 can be full of water, provided that some air space is needed in thetank 28 to facilitate level control and fluctuations in the tank 28.Thermal isolation can be accomplished in the tank 28, at least in part,by controlling the delivery of the hot return water from the recoverycoil 20 into the two suction bays 40, 42 and managing the flow currentsin the tank 28 to prevent convective mixing. As shown in FIG. 3, thedividing baffle 48 is used to physically separate at least a portion ofthe suction bays 40, 42 from one another. It is recognized that thedividing baffle 48 can be excluded from the tank 28 and otherdesigns/features can be used as an alternative or in addition to thebaffle 48 to thermally isolate e two suction bays 40, 42.

The tank 28 can include a diverter 66, 68 in each of the bays 40, 42,respectively. The EC discharge water can enter the tank 28 through thebreak tank 44 and flow into the space between the diverters 66, 68 and aback wall 70 of the tank 28. An opening exists between the diverters 66,68 and between an end of the baffle 48 and the diverters 66, 68. Theseopenings allow the cold water entering the tank 28 to flow into the bays40, 42. Such openings can be fixed or variable. For example, the baffle48 can include a sliding plate such that the distance between the end ofthe baffle 48 and the diverters 66, 68 can be changed.

For the hot return water (from the recovery coil) entering the suctionbays 40, 42 through valves 54, 56, such hot return water can be addedinto suction bays 40, 42 using different fluid designs and features tomanage how the hot return water is introduced into the suction bays 40,42. Examples of such designs/features are described below in referenceto FIGS. 4-7.

FIG. 4 shows an underside 71 of the cover 43 for the second pump suctionbay 42. The cover 43 can have a front end 72 that is aligned with thefront end 49 of the 28 tank (when the cover 43 is on the tank 28) and aback end 73 that is aligned with the back end 46 of the tank 28 (whenthe cover 43 is on the tank 28). FIG. 4 also shows a discharge pipe 74.The discharge pipe 74 can be connected to the valve 56 and piping 58shown in FIG. 2 such that hot return water from the recovery coil canflow through the piping 58 and into the discharge pipe 74. The dischargepipe 74 can deliver the hot return water into the second pump suctionbay 42. The discharge pipe 74 can include an elbow 76, tubing 78, andcap 80. In an example, a hanger 82 can be used to attach the tubing 78to the underside 71 of the cover 43.

In an example, the tubing 78 can include a diffuser slot 84 formed inthe tubing 78 for releasing/delivering the hot return water from thedischarge pipe 74 and into the pump suction bay 42. FIGS. 5 and 6 show asimplified schematic of the pump suction bay 42 and the discharge pipe74 to illustrate the diffuser slot 84.

FIG. 5 is a side view of the discharge pipe 74 and FIG. 6 is a top viewof the discharge pipe 74. In the example shown in FIGS. 5 and 6, thediffuser slot 84 can be formed in a side of the discharge pipe 74 at anangle of approximately 45 degrees, relative to a bottom surface 85 ofthe tank 28. As such, the water exiting the pipe 74 through the slot 84hits the bottom 85 of the tank 28 at an angle. In another example, thetubing 78 can be oriented such that the slot 84 faces the bottom 85 ofthe tank 28. It is recognized that various positions of the slot 84 canbe used to direct the water exiting the pipe 74 in a particulardirection.

It is recognized that other angles and configurations of the diffuserslot 84 can be used for the discharge pipe 74. The discharge pipe 74 isdesigned to control an orientation and/or direction at which the wateris introduced into the bay 42. It can be important to direct the hotreturn water toward the pump inlet 52. It can be important to control,and in some cases, minimize a velocity at which the hot return water isintroduced into the bay 42, to minimize turbulence inside the bay 42.For example, if the slot 84 points toward the bottom of tank 28,turbulence of the water at or near the surface of the water in the tank28 can be minimized or prevented.

As shown in FIGS. 5 and 6, the slot 84 is an elongated slot formed inthe tubing 78. In an example, a majority of the total length of thetubing 78 includes the slot 84. It is recognized that a length and widthof the slot 84 can be determined based in part on a target velocity ofthe water exiting through the slot 84. Although not specifically shown,the first pump suction bay 40 can include a similar discharge pipe tothe discharge pipe 74 shown in FIG. 4.

FIG. 7 illustrates another example of a tank 28B that can be used in theconditioning system 10. FIG. 7 is an alternative design for introducingthe hot return water from the recovery coil into first and second pumpsuction bays 40B, 42B. The tank 28B can be generally similar to the tank28 described above and shown in FIGS. 2-6. The tank 28B can include thesame general design and features with the exception that instead of thedischarge pipe 74 shown in FIGS. 4-6, the tank 28B can include a firstdiffuser 86 in the first pump suction bay 40B and a second diffuser 88in the second pump suction bay 42B. The first and second diffusers 86,88, in combination with an elbow 90 connected to each of the diffusers86, 88, are designed to slow down the fluid flow or reduce the velocityof the water as it is released into the respective bay 40B and 42B, andto direct the water to pump suction inlets 50B and 52B. A particularlocation for the diffusers 86, 88 within the respective bay 40B, 42B canvary depending in part on a target velocity of the water existing thediffuser 86, 88 and a desired distance of the diffusers 86, 88 from therespective pump suction inlet 50B, 52B.

Additional features can be used in addition to or as an alternative tothose included in the design of the tank 28, 28B in FIGS. 2-7 to controlthe distribution and flow of water in the tank 28, 28B and through thefirst and second pumps 30, 32 (P-1, P-2).

FIG. 8 is a simplified schematic of the conditioning unit 10 includingthe tank 28 and the fluid flow paths into and out of the tank 28. FIG. 8also schematically shows the evaporative cooler (EC) 18, recovery coil(RC) 20 and heat load 92, relative to the various flow paths. Thedistribution of the hot return water from the RC 20 to the first andsecond pump suction bays can depend on an operating mode of theconditioning system 10. For simplicity, FIG. 8 does not show thestructural components of the tank 28, including the first and secondpump suction bays. Thus, for the description below of operating in thevarious modes, reference is made to the other figures included hereinand described above. FIG. 8 can be applicable to various designs of thetank 28, including the example shown in FIGS. 4-6 or the example shownin FIG. 7.

FIG. 8 shows a three-way valve 94 for modulating a flow from the RC 20to the first and second pump suction bays of the tank 28. The three-wayvalve 94 can be used in place of the two-way valves 54, 56 shown in FIG.2.

In the economizer mode, one or both of the valves 54, 56 (or one or bothsides of the valve 94) can be open such that the return water from therecovery coil 20 can flow through the valves 54, 56 (or both sides ofthe valve 94) into either suction bay 40, 42 of the tank 28. Theeconomizer mode operates in conditions in which the outdoor air cansufficiently cool the hot water from the heat load 92. Thus thetemperature of the return water from the recovery coil 20 in theeconomizer mode is not warm or hot in the outdoor air conditions underwhich the economizer mode is used. After the water from the recoverycoil 20 flows into the tank 28, all supply water can be pumped by thefirst pump 30 (P-1) to the cold water main 12. In the economizer mode,the second pump 32 (P-2) can be off since the evaporative cooler 18 isnot used in that operating mode. The tank level can be sensed by a tanklevel sensor and controlled in part by an RC-fill valve 96 (or controlvalve, CV).

In the adiabatic mode, the water from the recovery coil 20 can flow onlythrough the valve 54 into the first suction bay 40. In contrast to theeconomizer mode, the second pump 32 (P-2) can be on in the adiabaticmode and the second pump 32 (P-2) can pump a recirculating flow of waterthrough the evaporative cooler 18 and back into the tank 28 via thebreak tank 44. The rear or back 46 of the tank 28 can be flooded withcold water. Generally all or close to all of the cold water from the EC16 can naturally flow into the second pump suction bay 42 since thefirst pump suction bay 40 can be supplied with water from the recoverycoil 20. Under the single tank design, the adiabatic mode is not acompletely closed fluid circuit; however, the control of the flow ofwater in the tank 28 as described immediately above can generallyseparate the EC discharge water from the recovery coil return water.

In the evaporative mode, all water from the recovery coil 20 can bediverted through the valve 56 into the second pump suction bay 42.Because the second pump suction bay 42 is filled with hot water, thecold discharge water from the evaporative cooler 16 can naturally flowinto the first pump suction bay 40. The flow of cold water into thefirst pump suction bay 40 can be in proportion to a pumping rate of thefirst pump 30 (P-1), with any remaining water flowing back to the secondpump suction bay 42. To ensure that all the RC return water flows to thesecond pump inlet 52, a flow rate of the second pump 32 (P-2.) should begreater than a flow rate of the first pump 30 (P-1). An overall tanklevel can be controlled by the RC-fill valve 96.

The blended mode operation can involve varying the distribution of hotreturn water from the recovery coil 20 into the two pump suction bays40,42 and corresponding pump suction inlets 50, 52, and consequentlyvarying the mix ratio of warm and cold water into the pumped cold watersupply (to the heat load 92) via the pump 30 and into the pumpedrecirculated water (to the evaporative cooler 16) via the pump 32. Thevalves 54, 56 (or the 3-way valve 94) can control the proportion of hotreturn water going into the suction inlets 50, 52 for the pumps 30, 32,respectively (P-1, P-2).

The conditioning unit 10 can be controlled to maintain a supply watertemperature set point under varying ambient air conditions or varyingcooling loads. The conditioning unit 10 accomplishes this by varying themix ratio of EC discharge water and RC return water into the pumpsuction bays 40, 42. For example, if the conditioning unit 10 enters thewet mode of operation in the equivalent of the adiabatic mode (100% ofRC return water into the first pump suction 40 and 100% evaporativecooler discharge into the second pump suction 42) and the ambientoutdoor air conditions rise (increased temperature or humidity), thesupply water temperature delivered by the first pump 30 (P-1) may riseabove the set point. In this case, the controller 38 of the unit 10 canbegin to modulate the RC return valves 54, 56 to divert a portion of thereturn water into the second pump suction bay 42, which can cause anequivalent portion of cold EC discharge water to flow into the firstpump suction bay 40, lowering the supply water temperature to the setpoint. The mix ratio can be continuously modulated by the controller 38to maintain supply water temperature set point in response to varyingambient conditions and load. At peak ambient conditions or peak coolingloads the conditioning unit 10 may operate in the equivalent of theevaporative mode (100% of RC return water into P-2 suction, and P-1suction being supplied essentially all by EC discharge water).

If a pre-cooler 16 is included in the conditioning unit 10, thepre-cooler 16 can selectively be used in any of the adiabatic mode,evaporative mode, or blended mode. When the pre-cooler 16 is used in theevaporative mode, the operating mode can be referred to as an enhancedor super-evaporation mode. The pre-cooler 16 can precondition theoutdoor air and can be effective particularly in hot or humidconditions.

The modulation of the water mix ratio can be used to control the supplywater temperature and evaporation rate in the evaporative cooler 18.Because capacity modulation can be accomplished by varying water mixratio, airflow modulation may not be needed in the evaporative (wet)mode of operation. When the conditioning unit transitions from theeconomizer mode to the wet mode, the air flow rate (fan speed) can beheld constant, and the supply water temperature can be controlled by themix ratio. The conditioning unit 10 can be optimized for power or waterefficiency by changing the fan speed setting in the wet mode. Thehighest water efficiency occurs when the fan speed is maximized, and thehighest power efficiency occurs when the fan speed is minimized.

The mixing of the EC discharge water (entering the break tank 44) andthe RC discharge water (entering into one or both of the suction bays40, 42) can be varied in order for the water at the first suction pumpinlet 50 to be at or near the setpoint temperature. As the outdoor airconditions change, the temperature of the EC discharge water changes.Similarly, the temperature of the RC discharge water changes as afunction of the outdoor air conditions. Thus the mix ratio of the twowater sources (EC discharge water and RC discharge water) provided tothe first pump suction inlet 50 is changing to achieve the temperaturefor the cold water supply from the first pump 30.

At peak cooling, the unit 10 can he controlled to minimize any warmwater (RC discharge water) going into the first pump suction inlet 50for delivery by the first pump 30. If the flow rate of the second pump32 is high or increased, the hot/warm water can be drawn into the secondpump 32 and any cold water can flow to the back 46 of the tank 28 atwhich point it can be available) be withdrawn from the tank 28 by thefirst pump 30.

The system controller 38 can make various adjustments in order tomaintain the supply water temperature (from the first pump 30) at ornear the setpoint temperature, based on the demands of the heat load 92and outdoor air conditions. In an example, the water mix ratio can beadjusted in discrete steps (for example, 10%, 20%, 30%, etc.), and theprecise control of the supply water temperature can be done by air flowmodulation (for example, via one or more fans). In another example, theair flow rate can be fixed and the water mix ratio can be preciselymodulated such that the supply water temperature stays at or near theset point temperature. It is recognized that additional parameters canbe controlled to maintain the supply water temperature at or near thesetpoint temperature. Another possible control parameter can include,for example, varying the flow rate through the evaporative cooler.

FIGS. 9 and 10 are psychometric charts for conditionings units operatingwithout the blended mode and under the same outdoor air conditions. FIG.9 shows the conditioning unit operating under the adiabatic mode for aparticular set of outdoor or ambient air conditions. FIG. 10 shows thesame conditioning unit operating under the evaporative mode under thatsame set of outdoor or ambient air conditions. Under both modes, theconditioning unit is able to provide sufficient cooling such that thecold water supply to the heat load is at or near the set pointtemperature of 26.7 degrees Celsius. The evaporative cooler (EC) in theconditioning unit of FIGS. 9 and 10 is a liquid-to-air membrane energyexchanger (LAMEE). ECwi is the water at the inlet of the evaporativecooler. ECwo is the water at the outlet of the evaporative cooler. ECaiis the air at the inlet of the evaporative cooler. ECao is the air atthe outlet of the evaporative cooler. Similarly, RCwi is the water atthe inlet of the recovery coil, and RCwo is the water at the outlet ofthe evaporative cooler. RCai is the air at the inlet of the evaporativecooler. RCao is the air at the outlet of the evaporative cooler.

In the adiabatic mode, the water circuits for the EC and the RC aregenerally separate. In the adiabatic mode shown in FIG. 9, the majorityof the heat rejection is occurring in the recovery coil. The fans haveto ramp up to a scavenger air flow rate of 35,000 ACFM. In contrast, inthe evaporative mode shown in FIG. 10, the majority of the cooling isprovided by the evaporative cooler. The water at the inlet of theevaporative cooler is the same as the water at the outlet of the RC, asshown in FIG. 10. The water outlet temperature of the evaporative cooleris not visible in FIG. 10 since it is at or near the set pointtemperature of 26.7 degrees Celsius. Although the fans can be rampeddown in the evaporative mode to a scavenger air flow rate of 10,400ACFM, the conditioning unit consumes much more water under theevaporative mode shown in FIG. 10, as compared to the adiabatic mode ofFIG. 9.

FIGS. 9 and 10 illustrate the operating extremes of the adiabatic modeand the evaporative mode under a particular set of outdoor airconditions in which each mode can handle the heat load but at theexpense of power consumption or water consumption. Moreover, switchingfrom the adiabatic mode to the evaporative mode or vice versa as theoutdoor air conditions change can result in significant changes in howthe conditioning unit is operated. The blended operation mode canprovide significant advantages when it is used in the outdoor or ambientair conditions shown in FIGS. 9 and 10. The blended operation mode canprovide finer control and stability and can continue to be used aschanges in the outdoor air changes are occurring, without having tofully cross over from the adiabatic mode to the evaporative mode or viceversa.

The capability to operate in the blended mode, as described herein, isapplicable to any operation with evaporative cooling or cooling towers.In addition to the advantages provided above, such blended mode canprovide smooth control of the unit cooling capacity and supply watertemperature in the wet mode of operation. As such, the supply watertemperature can be controlled more precisely.

The blended mode can result in higher annual water usage efficiency ofthe conditioning unit or overall conditioning system. FIG. 11 showsmodeling results of the annual water consumption of two systems, each ofwhich have 32. units. Each of the 32 units can be similar to theconditioning unit 10 of FIG. 1 and the evaporative cooler can include aLAMER The system with the tank blending capabilities described herein isprojected to consume 19.9 million gallons of water annually. The systemwithout tank blending is projected to consume 31.3 million gallons ofwater annually. Thus the system having multiple units with a blendedoperation mode exhibited more than a 35% reduction in annual water usageas compared to a conditioning system having the same number of units,but without blended operation.

FIG. 12 is a simplified schematic (similar to FIG. 8) of a conditioningunit 100 that can be configured and operate similarly to theconditioning unit 10. The conditioning unit 100 can include anevaporative cooler 118 (EC) and a recovery coil 120 (RC). It isrecognized that, like the conditioning unit 100 having multipleevaporative coolers and multiple recovery coils (see FIG. 1), EC 118 andRC 120 of FIG. 12 can represent one or more of that particularcomponent. Also, the conditioning unit 100 can include one or morepre-coolers (see the pre-coolers 16 of FIG. 1) even though not includedin FIG. 8.

Instead of a single tank design, the conditioning unit 100 can includetwo tanks—a first tank 127 and a second tank 129. The two tanks 127, 129can be used to regulate a flow of hot water from the RC 120 into each ofthe tanks 127, 129, as well as to regulate a flow of cold water from theEC 118 into each of the tanks 127, 129. The conditioning unit 100 caninclude a system controller similar to the controller 38 of theconditioning unit 10. The conditioning unit 100 can include anequalization valve 193 located between the first and second tanks 127,129.

The first tank 127 can be referred to as the “cold” tank since the waterfrom the first tank 127 is delivered via a first pump 130 as the coldwater supply for the heat load. The second tank 129 can be referred toas the “hot” tank since the water from the second tank 129 is deliveredvia a second pump 132 for recirculation through the EC 118. The flow ofRC return water from the recovery coil 20 to the first and second tanks127, 129 can generally be the same as described above in reference tothe delivery of RC return water to the first and second pump suctionbays 40, 42 of the tank 28. FIG. 12 includes a first valve 154 for thefirst tank 127 and a second valve 156 for the second tank 129. The firstvalve 154 can be a first hot water valve (H1) and the second valve 156can be a second hot water valve (H2). It is recognized that in anotherexample, the unit 100 can include a three-way modulating valve forvarying and controlling the flow of RC return water to the first andsecond tanks 127, 129.

The conditioning unit 100 can include two cold water valves—a first coldwater valve 195 and a second cold water valve 197. The first cold watervalve 195 can be configured to deliver EC water to the first tank 127and the second cold water valve 197 can be configured to deliver ECwater to the second tank 129. The system controller for the conditioningunit 100 can vary and control the amounts of cold water delivered intoeach of the tanks 127, 129, depending on an operating mode of the unit100.

In an economizer mode, the RC return water can flow through the valve154 and into the first tank 127 and then can be pumped to the cold watermain using the pump 130. The outdoor air conditions under the economizermode can be such that the RC return water can be used as cold watersupply for the heat load.

In an adiabatic mode, the first tank 127 can continue to operate asdescribed in the paragraph immediately above in reference to theeconomizer mode. The second tank 129 can be filled with the waterexiting the EC 118 and the second pump 132 can recirculate the waterfrom the second tank 129 back through the EC 118. The equalization valve193 can remain closed during operation in the adiabatic mode. Assimilarly described above for operation of the unit 10 in the adiabaticmode, the water circuits for the recovery coil 120 and the evaporativecooler 118 can remain essentially separate from one another in theadiabatic mode. The level in the second tank 129 can be sensed via asensor and make up water can be supplied to the second tank 129 asneeded.

In an evaporative mode, the equalization valve 193 can be open tofluidly connect the two tanks 127, 129 and the RC return water can besupplied to the second tank 129 through the second valve 156. The ECwater can be delivered into the first tank 127 via the first cold watervalve 195 at a flow rate in proportion to the pumping rate of the firstpump 130. Any remaining EC water can flow into the second tank 129 viathe second cold water valve 197. Overall tank operating level can becontrolled by a RC-fill valve similar to the RC fill valve 96 of FIG. 8.

In a blended operation mode, between the adiabatic mode and theevaporative mode, the first and second hot water valves 154, 156 can bemodulated to vary the distribution of the RC return water to the firstand second tanks 127, 129. As described above in reference to the unit10 and a single tank design, the blended operation mode can continuouslymonitor and adjust the distribution of the RC return water to the firstand second tanks 127, 129 such that the cold water supply temperature tothe heat load (as delivered from the tank 127 via the pump 130) is at ornear the set point temperature. In an example, the distribution ratiocan be continuously varied (and finely tuned) and the scavenger air flowrate through the conditioning unit can be relatively constant. Under theblended operation mode, the mix of hot return water from the RC 120 andcold discharge water from the EC 118 can be adjusted such that the watersupply temperature is at or near the set point temperature. The amountof cold discharge water entering each of the tanks 127, 129 can dependin part on the amount of hot return water entering each of the tanks127, 129 via the valves 154, 156.

In the single tank design, the back end or discharge area of the tank 28can receive the EC discharge water or cold water, and such dischargearea of the tank 28 can be fluidly connected to each of the first andsecond bays 40, 42 of the tank. In the two-tank design, each tank 127,129 can include a discharge area that can be in fluid connection withthe area of the tank 127, 129 that receives the RC return water via thevalves 154, 156.

In an example, the first and second tanks 127, 129 can be whollyseparate structures from one another. In another example, the first andsecond tanks 127, 129 can be part of the same structure, but physicallyseparated by a wall or other physical divider that runs a length of thetanks 127 and 129 (as compared to the dividing baffle 48 of the tank 28which does not run an entire length of the tank 28).

The two-tank design shown in FIG. 12 may provide better thermalisolation as compared to the tank 28, since the two-tank design canprevent undesirable mixing of the cold and hot water under particularoperating modes. The two-tank design can include additional equipment,including an additional tank, piping and valves, and consequentlyadditional parameters to control, relative to the single tank design.

FIG. 13 is a schematic of a conditioning unit 200 that can be configuredto generally operate similar to the conditioning units 10 and 100 toprovide cooling. The conditioning unit 200 can have a different systemfor operating in the blended mode, compared to the conditioning units 10and 100. The conditioning unit 200 can include an evaporative cooler 218(EC) and a recovery coil 220 (RC). It is recognized that, like theconditioning unit 100 having multiple evaporative coolers and multiplerecovery coils (see FIG. 1), EC 218 and RC 220 of FIG. 13 can representone or more of those particular components. The conditioning unit 200can include one or more pre-coolers (see the pre-coolers 16 of FIG. 1)even though not included in FIG. 13.

The conditioning unit 200 can include a manifold 203, rather than a oneor two tank design, for enabling the unit 200 to operate in the blendedmode between the adiabatic mode and the evaporative mode. The manifold203 can offer additional benefits, as provided below, to the design andoperation of the conditioning unit 200.

As described above in reference to the conditioning units 10 and 100,the unit 200 can provide cold water to a heat load. Such cold water cancome from the evaporative cooler 218 or the recovery coil 220, dependingon an operating mode of the unit 200. The cold water can be pumped tothe heat load via a first pump 230 as cold water supply (CWS) through awater line 205. After providing cooling to the heat load, the water canbe returned to the recovery coil 220 as hot water (HWR in FIG. 13) via aline 207. A second pump 232 can supply water to the evaporative cooler218 via an inlet line 209. The supply water to the evaporative cooler218 can be recirculated water from the evaporative cooler 218 or waterfrom the recovery coil 220, depending on the operating mode. The firstpump 230 can be included within the conditioning unit 200 or external tothe conditioning unit 200. In an example, the cold water supply can bedrained from the unit 200 and into external piping, and the pump 230 canbe a distribution pump located external to the unit 200.

The manifold 203 can enable distribution of water to the first pump 230and the second pump 232 from the evaporative cooler 218 and the recoverycoil 220. The manifold 203 can include an EC conduit 211 (also referredto as an EC discharge line 211) and a main conduit 213 (also referred toas common piping 213). The EC conduit 211 and the main conduit 213 canbe connected; such connection can include, for example, a T-junction215, as shown in FIG. 13. The main conduit 213 can include four pipingsections 213A, 213B, 213C and 213D, described below. The manifold 203can include a RC discharge line 217, which can include a junction 219for the water from the RC discharge line 217 to be distributed to piping221 and/or piping 223, depending on the operating mode. The piping 221can be a first RC conduit and include a first valve 225 and the piping223 can be a second RC conduit and include a second valve 231. Thepiping 221 can connect to the main conduit 213 at a junction 233 betweenpiping sections 213A and 213B. The piping 223 can connect to the mainconduit 213 at a junction 235 between sections piping 213C and 213D. Themanifold 203 can include a pressure control device 237 in fluidconnection with the main conduit 213 via connector piping 239 (orreservoir conduit 239). The connector piping/reservoir conduit 239 canbe a short pipe that connects with the main conduit 213 at or inproximity to the junction 215 between the EC conduit 211 and the mainconduit 213.

In an example and as shown in FIG. 13, the pressure control device 237can be a reservoir for holding water. Other types of pressure controldevices or regulators can be used in the manifold 203 for controllingthe pressure at the junction 215 in order to control a back pressure ofthe evaporative cooler 218. This is described further below.

The piping section 213A can be located between the first pump 230 andthe junction 233. The piping section 213B can be located between thejunction 233 and the junction 215. The piping section 213C can belocated between the junction 215 and the junction 235. The pipingsection 213D can be located between the junction 235 and the second pump232.

The design of the piping in the manifold 203, as well as the valves 225and 231, can enable the distribution and control of water from theevaporative cooler 218 and recovery coil 220 to the first and secondpumps 230, 232, depending on the operating mode. The main conduit 213and the valves 225 and 231 can be used to effectively control the flowof water through the unit 200 and such flow varies as a function of theoperating mode. The valves 225 and 231 can be part of a flow controlsystem for variably distributing the flow of water from the recoverycoil outlet to the heat load and the evaporative cooler 218.

Under the adiabatic mode, essentially all or nearly all of the waterfrom the evaporative cooler 218 can flow into the main conduit 213 andthrough the second pump 232 for recirculation back to the evaporativecooler. In this mode, the second valve 231 can be completely closed andthe first valve 225 can be completely open such that essentially all ofthe water exiting the recovery coil 220 in the RC discharge line 217 canflow through the first valve 225 and into the piping section 213A, theninto the first pump 230 for delivery to the heat load.

Under the evaporative mode, essentially all or nearly all of the waterfrom the evaporative cooler 218 can flow into the piping sections 213Aand 213B and through the first pump 230 for delivery to the heat load.In this mode, the first valve 225 can he completely closed and thesecond valve 231 can be completely open such that essentially all of thewater in the RC discharge line 217 can flow through the second valve 231and into the piping section 213D, then into the second pump 232 forcirculation through the evaporative cooler 218 via the line 209.

Under the blended mode, a portion of the recovery coil water in thedischarge line 217 can go to the heat load and the remaining portion cango to the evaporative cooler 218. Similarly, a portion of theevaporative cooler water in the EC conduit 211 can go to the heat loadand the remaining portion can be recirculated through the evaporativecooler 218. As such, the first and second valves 225, 231 can both bepartially open and the particular position of each valve can bedetermined based on the ratio of water from the recovery coil 220 andthe evaporative cooler 218 to the heat load. Such ratio can vary duringoperation in the blended mode in order to maintain the supply watertemperature set point, as described above in reference to theconditioning unit 10. The conditioning unit 200 can include a systemcontroller that can function similar to the controller 38 tocontinuously modulate the mix ratio in response to changing ambientconditions and load. The flow control system or device for controllingthe valves 225, 231 can be part of the system controller or incommunication with the system controller.

The position of the first and second valves 225, 231 in the blended modecan control the distribution of water from the recovery coil 220 to thefirst pump 230 and the second pump 232. More specifically, the positionof the valves 225, 231 can control the distribution of water from therecovery coil 220 to the heat load and to the evaporative cooler 218. Inthe blended mode, the water to the heat load is a mix of water from therecovery coil 220 and water from the evaporative cooler 218; similarly,the water to the inlet of the evaporative cooler 218 (via the line 209)is a mix of water from the recovery coil 220 and water from theevaporative cooler 218 that is recirculated back through the evaporativecooler, The water exiting the evaporative cooler 218 in the EC conduit211 can flow towards the pump 230 (via the section 213B) and/or the pump232 (via the section 213C) once the evaporative cooler outlet waterreaches the junction 215. The distribution of such water from theevaporative cooler 218 can depend on the amount of the recovery coiloutlet water going to each of pumps 230 and 232. Each of pumps 230 and232 can have a set flow rate, and such flow can include recovery coiloutlet water, evaporative cooler outlet water or both. Thus, afteraccounting for the recovery coil outlet water (controlled via valves 225and 231), the remaining water to be drawn into each of the pumps 230 and232 can be evaporative cooler outlet water.

The manifold 203 can enable back pressure control of the evaporativecooler 218. As described above, in an example the evaporative cooler 218can include a liquid to air membrane energy exchanger (LAMEE). Given thedesign of the LAMEE, an important operating parameter is low pressure atthe LAMEE outlet. For example, the LAMEE can be operated such that thepressure is maintained at 0.5 psi or lower with minimal fluctuations.The manifold 203 can include a pressure control or regulation device,such as the reservoir 237, which in combination with the piping in themanifold 203 can control the back pressure of the evaporative cooler218.

The water exiting the evaporative cooler 218 (via the discharge line/ECconduit 211) can flow into the main conduit 213 such that the water canflow to the first pump 230 or the second pump 232, depending on theoperating mode. The reservoir 237 can contain water at a specific levelthat results in pressure on the connector piping 239, which is connectedto the main conduit 213. Because the connector piping 239 is fluidicallyconnected and in proximity to the EC conduit 211 at the junction 215,the pressure of the water in the connector piping 239 can controlpressure at the junction 215, which is essentially the back pressure forthe evaporative cooler 218 or the pressure in the EC conduit 211. Thepressure in the connector piping 239 can be controlled closely bymonitoring the water level in the reservoir 237.

In an example, the valves 225 and 231 can be used to regulate the waterlevel in the pressure control device/reservoir 237. The valves 225 and231 can be modulated closed or open together to raise or lower the waterlevel in the reservoir 237.

The junction 215 is shown in FIG. 13 with the EC conduit 211 being inalignment with the connector piping 239. It is recognized that theconnector piping 239 is not required to connect to the main conduit 213specifically at the junction 215 so long as the connector piping 239connects to the main conduit 213 at a location in proximity to thejunction 115.

The design of the manifold 203 can help to prevent air entrainment whenthe water is pumped through the first and second pumps 230, 232. Thepiping in the manifold 203, which is essentially completely enclosed,can be flooded in order to minimize or prevent air entrainment. At leasta portion of the piping in the manifold 203, including the main conduit213, can be at an elevation that is lower than the waterline in thereservoir 237 to ensure that the conduit or piping 213 can be fullyflooded with water. By contrast, air entrainment in a tank design can bemore difficult to control, particularly in a shallow tank in which thepump suction draws a large flow rate and there is the potential forvortex generation and agitation or splashing which can entrain airbubbles.

In the example in which the pressure control device of the manifold 203is a reservoir, the reservoir can provide additional functionalityduring the switch over from economizer mode to adiabatic mode or viceversa, from adiabatic mode to economizer mode. To switch to adiabaticmode, the evaporative cooler 218 is filled up with water. Conversely, toswitch to economizer mode, the water in the evaporative cooler 218 isdrained. The reservoir 237 can be used to provide water to theevaporative cooler 218 during start up (to adiabatic mode) or to housewater from the evaporative cooler 218 during shut down (to economizermode). The connector piping 239 and other piping in the manifold 203 canenable the ability to get water in and out of the reservoir 237 for theevaporative cooler 218

The enclosed design of the manifold 203 can help to minimize thermallosses and can operate more effectively than a tank design in whichturbulence and the formation of eddies in the tank can contribute tomixing of hot and cold water. Despite the enclosed or sealed pipingdesign, the main conduit 213 is configured such that hot and cold watercan flow between the first and second pumps 130, 132 (i.e. both hot andcold water can flow in both directions within the piping 213) and thusthere is still the potential for mixing of hot and cold water in themain conduit 213.

Particularly during peak conditions under the evaporative mode, when theconditioning unit 200 is providing maximum cooling to meet the demandsof the heat load, thermal loss can degrade the performance of the unit200. As such, in the evaporative mode, effective operation of the unit200 can include preventing hot water from the recovery coil 220 (whichis going to the second pump 232) from leaking into the cold water supply(from the evaporative cooler 218 (which is going to the first pump 230).Such leaking can occur, for example, in the piping sections 213B and213C.

Leaking or mixing of hot water into the cold water supply can beprevented by controlling the flow rates within the unit 200 and morespecifically, having different flow rates at different sections of theunit 200. The flow rate through the second pump 232 can be greater thanthe flow rate through the first pump 230. For example, if the first pump230 is pulling water at 400 gallons per minute for the cold water supplyto the heat load, the second pump 232 can be set to pull water at 420gallons per minute to the evaporative cooler 218. Thus, there is anextra 20 gallons per minute of cold water exiting the evaporative cooler218 that is not needed by the first pump 230 for the cold water supply.Such extra or excess cold water can go through the section 213C of themain conduit 213 and towards the second pump 232. As such, the extracold water can serve to hold the hot water (from the recovery coil 220)back and prevent the hot water from mixing with cold water going to theheat load.

FIG. 14 is a schematic of a conditioning unit 300 that can he configuredto generally operate similar to the conditioning unit 200 of FIG. 13.The unit 300 can include an evaporative cooler 318 having an inlet line309 and an EC conduit/discharge line 311, a recovery coil 320 having adischarge line 317, a manifold 303, and first and second pumps 330, 332.A supply line 305 can deliver cold water (cold water supply, CWS) to aheat load. A return line 307 can deliver hot return water from the heatload to the recovery coil 320.

The manifold 303 can include a three-way modulating valve 345 forcontrolling a distribution of the water in the RC discharge line intopiping 321 (or first RC conduit 321) and piping 323 (or second RCconduit 323). The three-way valve 345 can be part of a flow controldevice of the manifold 303 and can be used in place of the first andsecond valves 225, 231 shown in FIG. 13, The position of the valve 345can be controlled based on the operating mode of the unit 200.

The manifold 303 can include common piping/main conduit 313 which caninclude piping sections 313A, 313B, 313C and 313D. The EC conduit 311can connect to the common pipe 313 at a junction 315. The piping 321 canconnect to the main conduit 313 at a junction 333 and the piping 323 canconnect to the main conduit 313 at a junction 335.

The manifold 303 can include a first pressure control device/reservoir351 and a second pressure control device/reservoir 355. The firstreservoir 351 can be in fluid connection with the main conduit 313 viafirst connector piping 353 (or first reservoir conduct 353) and thesecond reservoir 355 can be in fluid connection with the main conduit313 via second connector piping 357 (or second reservoir conduit 357).The pressure control devices 351 and 355 can operate similar to thepressure control device 237 shown in FIG. 13. The first connector piping353 and second connector piping 357 can be short piping sections thatcan each be located in proximity to the junction 315 such that theconnector piping 353, 357 can be used to control the back pressure ofthe evaporative cooler 318.

FIG. 14 provides another example, in addition to FIG. 13, of a manifolddesign for operating a conditioning unit in the various modes describedherein, including a blended mode of the adiabatic and evaporative modes.FIG. 14 shows a three-way valve and two reservoirs in the manifold, Itis recognized that a manifold design can include, in one example, thetwo valves 225, 231 in FIG. 13 with a two-reservoir design and, inanother example, can include the three-way valve 345 with a singlereservoir design.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

All publications, patents, and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim. Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, the code can be tangibly stored on one ormore volatile or non-volatile tangible computer-readable media, such asduring execution or at other times. Examples of these tangiblecomputer-readable media can include, but are not limited to, hard disks,removable magnetic disks, removable optical disks (e.g., compact disksand digital video disks), magnetic cassettes, memory cards or sticks,random access memories (RAMs), read only memories (ROMs), and the like.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules may be hardware,software, or firmware communicatively coupled to one or more processorsin order to carry out the operations described herein. Modules mayhardware modules, and as such modules may be considered tangibleentities capable of performing specified operations and may beconfigured or arranged in a certain manner. In an example, circuits maybe arranged (e.g., internally or with respect to external entities suchas other circuits) in a specified manner as a module. In an example, thewhole or part of one or more computer systems (e.g., a standalone,client or server computer system) or one or more hardware processors maybe configured by firmware or software (e.g., instructions, anapplication portion, or an application) as a module that operates toperform specified operations. In an example, the software may reside ona machine-readable medium. In an example, the software, when executed bythe underlying hardware of the module, causes the hardware to performthe specified operations. Accordingly, the term hardware module isunderstood to encompass a tangible entity, be that an entity that isphysically constructed, specifically configured (e.g., hardwired), ortemporarily (e.g., transitorily) configured (e.g., programmed) tooperate in a specified manner or to perform part or all of any operationdescribed herein. Considering examples in which modules are temporarilyconfigured, each of the modules need not be instantiated at any onemoment in time. For example, where the modules comprise ageneral-purpose hardware processor configured using software; thegeneral-purpose hardware processor may be configured as respectivedifferent modules at different times. Software may accordingly configurea hardware processor, for example, to constitute a particular module atone instance of time and to constitute a different module at a differentinstance of time. Modules may also be software or firmware modules,which operate to perform the methodologies described herein.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. Also, in the above DetailedDescription, various features may be grouped together to streamline thedisclosure. This should not be interpreted as intending that anunclaimed disclosed feature is essential to any claim. Rather, inventivesubject matter may lie in less than all features of a particulardisclosed embodiment. Thus, the following claims are hereby incorporatedinto the Detailed Description, with each claim standing on its own as aseparate embodiment, and it is contemplated that such embodiments can becombined with each other in various combinations or permutations. Thescope of the invention should be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

Various aspects of the disclosure have been described. These and otheraspects are within the scope of the following claims.

What is claimed is:
 1. A conditioning system configured to providecooling to a heat load, the conditioning system comprising: a scavengerplenum having an air inlet and air outlet, the scavenger plenumconfigured to direct scavenger air in an air flow path from the airinlet to the air outlet; an evaporative cooler arranged inside thescavenger plenum in the air flow path and configured to circulate acooling fluid from an EC inlet through the evaporative cooler to an ECoutlet, the evaporative cooler configured to selectively evaporate aportion of the first cooling fluid when the conditioning system isoperating in an adiabatic mode or an evaporative mode, and theevaporative cooler is off or bypassed when the conditioning system isoperating in an economizer mode; a recovery coil arranged inside thescavenger plenum between the evaporative cooler and the air outlet andconfigured to circulate the cooling fluid from an RC inlet through therecovery coil to an RC outlet, the recovery coil configured to reduce atemperature of the cooling fluid using the scavenger air in the air flowpath, wherein the recovery coil provides sufficient cooling for the heatload in the economizer mode; and a fluid transmission and retentiondevice for receiving the cooling fluid from at least one of the ECoutlet and the RC outlet and variably distributing the cooling fluid toat least one of the heat load and the EC inlet based on the operatingmode and environmental conditions, the fluid transmission and retentiondevice including a flow control device for variable distribution of thecooling fluid to the heat load and the EC inlet.
 2. The conditioningsystem of claim 1 wherein the fluid transmission and retention deviceincludes a tank comprising a first portion and a second portion, thefirst and second portions at least partially separated from one another,and the tank further comprises a discharge area in fluid connection withat least one of the first and second portions.
 3. The conditioningsystem of claim 2 wherein the flow control device includes one or moremodulating valves between the RC outlet and the tank.
 4. Theconditioning system of claim 2 wherein the tank further comprises adividing baffle in the tank that partially separates the first portionand the second portion from one another, and the dividing baffle extendsalong a portion of a length of the tank.
 5. The conditioning system ofclaim I wherein the fluid transmission and retention device includes amanifold comprising: a main conduit connected to the EC inlet and theheat load, the main conduit configured to supply the cooling fluid tothe heat load; an EC conduit connected to the RC outlet and the mainconduit; a first RC conduit connected to the RC outlet and the mainconduit; a second RC conduit connected to the RC outlet and the mainconduit; and a pressure regulation device to control a pressure of thecooling fluid at the EC outlet, wherein the cooling fluid supplied tothe heat load comprises at least one of: substantially all of thecooling fluid from the RC outlet and substantially none of the coolingfluid from the EC outlet, substantially none of the cooling fluid fromthe RC outlet and substantially all of the cooling fluid from the ECoutlet, and a mixture of the cooling fluid from the RC outlet and thecooling fluid from the EC outlet.
 6. The conditioning system of claim 5wherein the EC conduit is connected to the main conduit between theconnection of the first RC conduit to the main conduit and theconnection of the second RC conduit to the main conduit.
 7. Theconditioning system of claim 1 wherein the evaporative cooler is aliquid-to-air membrane energy exchanger (LAMEE), and the cooling fluidis separated from the air flow path by a membrane, the LAMEE configuredto condition the scavenger air and evaporatively cool the cooling fluid.8. The conditioning system of claim 1 further comprising: a pre-coolerarranged inside the scavenger plenum between the air inlet and theevaporative cooler, the pre-cooler configured to selectively conditionthe scavenger air prior to passing the scavenger air through theevaporative cooler, based on the outdoor air conditions.
 9. A method ofcontrolling operation of a conditioning system configured to providecooling to a heat load, the conditioning system having an evaporativecooler and a downstream recovery coil arranged inside a scavenger plenumconfigured to direct scavenger air from an air inlet to an air outlet,the method comprising: selectively directing scavenger air through theevaporative cooler depending on environmental conditions, wherein theevaporative cooler circulates water through the evaporative coolerduring operation of the evaporative cooler; directing the scavenger airthrough the recovery coil, wherein the recovery coil circulates waterthrough the recovery coil; directing discharge water exiting theevaporative cooler at an EC outlet into a fluid transmission andretention device; directing return water exiting the recovery coil at anRC outlet into the fluid transmission and retention device; selectivelydirecting water from the fluid transmission and retention device to theheat load via a first pump fluidically connected to the fluidtransmission and retention device; and selectively directing water fromthe fluid transmission and retention device to the evaporative coolervia the second pump fluidically connected to the fluid transmission andretention device.
 10. The method of claim 9 wherein the fluidtransmission and retention device includes a tank having a first bay anda second bay, the first and second bays at least partially separatedfrom one another, and wherein directing return water exiting therecovery coil into the fluid transmission and retention device includesdirecting return water exiting the recovery coil into at least one ofthe first bay and the second bay based on the outdoor air conditions.11. The method of claim 10 further comprising: measuring a temperatureof water being supplied to the heat load via the first pump; andadjusting a distribution of the return water to the first and secondbays as a function of the measured temperature of the supply waterrelative to a set point temperature.
 12. The method of claim 9 whereinthe fluid transmission and retention device includes a manifoldcomprising: a main conduit fluidically connected to an EC inlet of theevaporative cooler and the heat load; an EC conduit fluidicallyconnected to the EC outlet and the main conduit; a first RC conduitfluidically connected to the RC outlet and the main conduit; a second RCconduit fluidically connected to the RC outlet and the main conduit; anda pressure control device for regulating a pressure of the cooling fluidat the EC outlet
 13. The method of claim 12 wherein selectivelydirecting water from the fluid transmission and retention device to theheat load includes supplying the water from the main conduit to the heatload, the water to the heat load comprising at least one of:substantially all of the water from the RC outlet and substantially noneof the water from the EC outlet; substantially none of the water fromthe RC outlet and substantially all of the water from the EC outlet; anda mixture of the water from the RC outlet and the EC outlet.
 14. Themethod of claim 9 further comprising: setting the first pump at a firstflow rate; and setting the second pump at a second flow rate, whereinthe first flow rate is higher than the second flow rate.
 15. Aconditioning system configured to provide cooling to a heat load andoperable in a plurality of operating modes, the conditioning systemcomprising: a scavenger plenum configured to direct scavenger air froman air inlet to an air outlet; an evaporative cooler arranged inside thescavenger plenum and configured to circulate a cooling fluid from an ECinlet through the evaporative cooler to an EC outlet and to exchangeenergy between the cooling fluid and the scavenger air; a recovery coilarranged inside the scavenger plenum between the evaporative cooler andthe air outlet and configured to circulate the cooling fluid from an RCinlet through the recovery coil to an RC outlet and to exchange heatbetween the cooling fluid and the scavenger air; and a manifoldconfigured to distribute the cooling fluid from at least one of the ECoutlet and the RC outlet to at least one of the EC inlet and the heatload based on the operating mode and environmental conditions, themanifold comprising: a main conduit fluidically connected to the ECinlet and the heat load; an EC conduit fluidically connected to the ECoutlet and the main conduit; a first RC conduit fluidically connected tothe RC outlet and the main conduit; a second RC conduit fluidicallyconnected to the RC outlet and the main conduit, the EC conduitconnected to the main conduit between the connection of the first RCconduit to the main conduit and the connection of the second RC conduitto the main conduit; a flow control device variably distributing thecooling fluid from the RC outlet to one or both of the first and secondRC conduits; and a pressure regulation device to control a pressure ofthe cooling fluid in the evaporative cooler.
 16. The conditioning systemof claim 15 wherein the cooling fluid supplied to the heat load from themain conduit comprises at least one of: substantially all of the coolingfluid from the RC outlet and substantially none of the cooling fluidfrom EC outlet; substantially none of the cooling fluid from the RCoutlet and substantially all of the cooling fluid from EC outlet; and amixture of the cooling fluid from the RC outlet and the cooling fluidfrom the EC outlet.
 17. The conditioning system of claim 15 wherein thecooling fluid to the EC inlet from the main conduit comprises at leastone of: substantially all of the cooling fluid from the RC outlet andsubstantially none of the cooling fluid from EC outlet; substantiallynone of the cooling fluid from the RC outlet and substantially all ofthe cooling fluid from EC outlet; and a mixture of the cooling fluidfrom the RC outlet and the cooling fluid from the EC outlet.
 18. Theconditioning system of claim 15 wherein the conditioning system isconfigured to operate in one or more of an adiabatic mode, anevaporative mode, and a blended mode; in the adiabatic mode, the flowcontrol device distributes substantially all of the cooling fluid fromthe RC outlet and substantially none of the cooling fluid from EC outletto the heat load; in the evaporative mode, the flow control devicedistributes substantially none of the cooling fluid from the RC outletand substantially all of the cooling fluid from EC outlet to the headload; and in the blended mode, the flow control device distributes amixture of the cooling fluid from the RC outlet and the cooling fluidfrom the EC outlet.
 19. The conditioning system of claim 15 wherein theEC conduit connects to the main conduit at a T-junction.
 20. Theconditioning system of claim 15, wherein the first RC conduit isconnected to the main conduit at a first RC junction on one side of theT-junction, and wherein the second RC conduit is connected to the mainconduit at a second junction on the other side of the T-junction. 21.The conditioning system of claim 15 wherein the pressure regulationdevice includes at least one reservoir having a controlled level ofwater and fluidically connected to the main conduit, the controlledlevel of water selected to set the pressure of the cooling fluid in theevaporative cooler.
 22. The conditioning system of claim 15 furthercomprising: a first pump fluidically connected to the manifold andconfigured to deliver the cooling fluid to the heat load; and a secondpump fluidically connected to the manifold and configured to deliver thecooling fluid to the EC inlet.
 23. The conditioning system of claim 15wherein the flow control device includes a first valve in the first RCconduit and a second valve in the second RC conduit.
 24. Theconditioning system of claim 15 wherein the flow control device includesa three-way modulating valve between the RC outlet and the first andsecond RC conduits.